Measurements of the electrical activity of the brain are, due to historical reasons, especially widespread in Europe and Russia within neurophysiologic and psychophysiologic diagnostics. Since 1960 the development regarding biofeedback treatment has for a large part been performed in the USA, Canada, Australia, Europe and Russia. As known within the field there exists both biological and technical methods for measuring and influencing different types of activities in the brain. The most common methods are: Electroencephalography (EEG), Hemoencephalography (HHG) and Magnetoencephalography (MEG). Within QEEG (quantitative EEG measurements) several mathematical models have been developed in order to measure discriminant functions that comprise: power-coherence, phase, IFTA pre vs. post treatment statistics, low RATE, instant coherence phase & Z-score biofeedback and others. QEEG is performed as a common EEG-recording, where an operator arranges several (21+) electrodes on the head of an individual in order to register a large part of the electrical activity of the brain at the same time. The brain activity is registered during a time period and functional assignements beyond the standard, eyes open and shut, may be added. The information is often compared to the activity which is analyzed by all of the various software systems that the operator has installed. The different types of software utilises different mathematical models for diagnosis, while others use systemic models, also called protocols, for treatment. Amongst other things, it is important that the electrodes in the QEEG system are placed in a correct manner, and that the contact between the electrodes and scalp is good. This is important in order to obtain an optimal basis for comparison between two measurements, or for comparing measurements from two or several individuals. Therefore, as a standard, the electrodes are placed in accordance with the international 10-20 system (described by for instance Erns Niedermeyer, Fernando Lopes da Silva, Electroencephalography: Basic Principles, Clinical Applications, and Related Fields, page 140). It is challenging to obtain the same result from two measurements. A more standardized system, than the sum of what exists today, would be very advantageous with regard to the further development of the science and research within this field.
Most EEG and QEEG systems today are based on elastic mesh and/or caps which are adapted to the 10-20 system, or other less known placement-charts. These caps are made in various designs with apertures for inserting electrodes. The caps are also made in several different sizes since the distance between the electrodes must be adapted to the size of the skull in accordance to the 10-20 system, or other placement-charts. The problem is often that these caps are not capable of furnishing the electrodes with enough pressure against the skull, due to hair and the shape of the skull. Caps that are tightened are often uncomfortable for the individual, and especially for sensitive children. Optimization is necessary to achieve a signal without too much background noise. Such noise will lead to less accurate measurements and information. The electrodes must also be placed manually in a correct manner with regard to the different sizes of the skull, and this is often time consuming and requires competence. Further, such manual placing of the electrodes increases the risk of placing the electrodes in an erroneously manner due to human failure.
Patent application US 2007/0106170 A1 discloses an electrode/sensor cap for use in EEG. Multiple inflatable bladders are used to achieve pressure on the electrodes. The technical solution of using inflatable bladders according to said application requires multiple caps adapted to individual skull sizes, and manual adaptation of the electrode placing is still necessary.
The Russian patent application SU 676273 A1 discloses an electrode/sensor cap for use in EEG. The technical solution for achieving adequate pressure on the electrodes is similar to the one disclosed in US patent application no. 2007/0106170 A1. The multiple bladders are here formed by joining the inner layer of the cap to the outer shell/layer in such a way that a discrete bladder is formed at each electrode. The drawbacks of said solution are the same as those mentioned for the US patent application no. 2007/0106170 A1.
Japanese patent application JP 2006-6667 A discloses an electrode/sensor cap for use in EEG. In one of the embodiments, a separate balloon situated between an inner hat and an outer helmet is inflated to provide pressure on the electrodes placed on the inner hat. The same drawbacks apply for the electrode/sensor cap of JP 2006-6667 A as the ones mentioned for patent application US 2007/0106170 A1
Measurements of the electrical activity of the brain are also used in a number of other areas in addition to neurophysiologic/psychophysiologic diagnostics and treatment. In the area of biotechnology it is possible, by using such measurements, to transform electrical impulses from the brain to electronic signals by the help of suitable sensors; such signals may in turn guide/control various technical systems. These technical systems may be for example fighter pilot helmets, speech synthesizers, robots, various entertainment systems such as computer games as well as other systems making use of brain-computer interfacing (BCI).
It is the purpose of the present invention to provide a device, and a method, for placing and securing sensors/electrodes on the head of an individual. Said device/method optimizes signal information and avoids some of the problems connected to the devices and methods in the prior art.